CN114823117A - Apparatus and method for continuous production of tape casting orientation - Google Patents

Abstract

The invention provides a continuous production flow casting orientation forming device and method, comprising electromagnets arranged above and below the casting base tape respectively; the two electromagnets are respectively fixed by brackets, and the electromagnets can be mounted on the brackets with the brackets as the The shaft rotates. Start the casting machine, the casting base belt starts to move, the upper and lower electromagnets start to rotate, and the current is increased to the set value. At this time, the casting slurry is poured into the casting base belt, and the casting starts. The base tape is dried and shaped after being oriented by a rotating magnetic field. It is called a green body by cutting, and it is called a finished product after being sintered in a muffle furnace at 1100-1300 °C. The magnetic field provided by the electromagnet of the present invention can be flexibly adjusted according to the material to be formed by changing the current. The use of the upper and lower electromagnets can make the distribution of the magnetic field in the middle region, especially in the thickness direction of the cast film, more uniform, which is beneficial to Reduce the resistance during particle orientation, thereby increasing the degree of orientation.

Description

Apparatus and method for continuous production of tape casting orientation

technical field

The invention belongs to the technical field of tape casting. In particular, it relates to a continuous production flow casting orientation forming device and method.

Background technique

Tape casting (also known as coating molding) is a common material molding method, suitable for making materials into long rolls, cloth, and sheets. Tape casting is often used to prepare thick films in circuits, or components in electronic components. The basic process of tape casting is to mix and stir the electronic material powder with other additives such as binders, dispersants, plasticizers, diluents, defoamers, etc. to form a flowing slurry, and then coat the slurry. On the moving carrier tape, a flat surface with a certain thickness is formed by a scraper, and the slurry is dried to form a sheet during the moving process.

Most of the magnetic materials have magnetocrystalline anisotropy. If the magnetic material is oriented and formed in a magnetic field, the final material has more excellent magnetic properties in the direction of the magnetic field than the material that is oriented and formed without a magnetic field. So there is a lot of design around how to do the magnetic field shaping during the casting process.

There is a solution (application number 201810985132.2) permanent magnet is placed in a non-magnetic sleeve, placed below the non-magnetic casting base tape, the direction of movement of the cast film on the base tape is perpendicular to the direction of the paper, when the material is When it is in the region just above the permanent magnet installation axis, the sheet-like magnetic material (black short thick line) in the cast film will be aligned under the action of the approximately constant magnetic field formed by the permanent magnet.

This method has certain limitations and disadvantages.

The first is that the device that provides the magnetic field uses a permanent magnet. Once the permanent magnet is fixed, the strength of the magnetic field it can provide cannot be changed. If the coercive force of the formed material is small, the required magnetic field will be very small. If the formed material has a large coercive force, the required magnetic field will be large, but the forming magnetic field is not as large as possible. A gradient magnetic field area is formed between the area near the magnet installation axis and the area far away from the magnet installation axis. In the gradient magnetic field area, the magnetic material will not only be oriented and its center of mass will also be stressed. If the gradient is too large, the center of mass will move. The condition is unfavorable for casting and will cause uneven thickness of the cast film. To sum up, when the formed material is replaced, the permanent magnet also needs to be replaced.

The second is that the device provides a single-direction magnetic field. For flake materials with large particle size, such as flake alloy powder (the size in the X-Y direction is 100 times the size in the Z direction), after orientation, the X-Y plane of the powder is basically the same as that of the cast substrate. In parallel, there is a reason for the gravity of the powder itself. If the particle size of sheet materials such as planar hexagonal ferrite (Y type, Z type) is small, and the size of the X-Y direction is not large enough (2-10 times) compared to the Z direction, if the magnetic field is only a unidirectional constant magnetic field, all the The X-Y plane of the grain is parallel to the tape cast, as shown in Figure 2, there will be a lot of powder standing up as shown on the right.

The second existing solution (application number 202010528169.X) is to place two permanent magnets in parallel with each other, the magnetic poles are opposite to each other, and the cast base tape passes through the middle of the two magnets. The middle position forms a magnetic field parallel to the cast substrate, and the material is oriented by the magnetic field when the substrate carrying the magnetic material passes through.

The first disadvantage of this solution is that the width of the cast film is limited by the size of the permanent magnet. The width of the cast film is the width of the magnet minus the length occupied by the support column. It is quite difficult to prepare a permanent magnet with a length of more than 300mm. , but the current industrial production of cast film width is generally more than 300mm, the mainstream is between 600-800mm, this design seriously affects its practical application.

The second disadvantage is similar to that of the prior art, the magnetic field formed by the device is still a single-direction magnetic field. For sheet materials such as planar hexagonal ferrite (Y-type, Z-type), the particle size is small, and the size in the X-Y direction is compared to Z The direction is not large enough (2-10 times), and it is also impossible to achieve that the X-Y planes of all grains are parallel to the cast substrate.

There is a third solution (application number 201911110135.2), which uses a pair of opposite electromagnets to provide a magnetic field, with the N pole of one electromagnet facing the S pole of the other electromagnet. The casting is carried out on a rotating platform. The slurry containing the magnetic material flows in from directly above, and rotates while flowing in. The slurry is spread out under the action of centrifugal force. At the same time of rotation, the electromagnet is activated, and the magnetic material is in the magnetic field. down orientation. In this design, the electromagnet is fixed, and the cast film is rotated. The cast film is equivalent to being magnetized by numerous magnetic fields in different directions in the plane. Therefore, for sheet materials such as plane hexagonal ferrite (Y-type, Z-type) particle size Small, and the X-Y direction size is not large enough (2-10 times) in the Z direction, the situation in Figure 2 will not appear.

The technical disadvantage of this solution is that the first casting cannot be performed continuously. When a circular casting film is formed, the film is shaped and needs to be removed and then re-placed for the substrate material, and the second film is cast. The production continuity is not strong and the efficiency is low. lower. The second cast film is circular, and only a square area in the middle can be used when making electronic components, as shown in Figure 3 below, which wastes a lot of area. Third, the volume of the electromagnet used to form a relatively uniform parallel magnetic field is large.

SUMMARY OF THE INVENTION

The technical purpose to be solved by the present invention is as follows for the above-mentioned existing technology:

The device has strong compatibility, the magnetic field is adjustable, and can adapt to various magnetic materials;

When forming, the X-Y plane of the sheet-like magnetic material particles with smaller particle size can be made parallel to the casting substrate;

It can meet the requirements of continuous production without interruption, and the design of the orientation device can be compatible with the current ordinary casting machine.

The technical scheme adopted in the present invention is:

The magnetic field of the tape casting orientation forming device which can be continuously produced comprises electromagnets arranged above and below the tape casting base respectively; the two electromagnets are respectively fixed by the brackets, and the electromagnets can be rotated on the brackets with the brackets as the axis.

The cross-section of the electromagnet is a chamfered rectangle.

The continuous production of the tape casting orientation molding method:

Mix and stir Z-type or Y-type ferrite powder with binder, plasticizer, dispersant and solvent to form a flowable casting slurry;

Start the casting machine, the casting base belt starts to move, the upper and lower electromagnets start to rotate, and the current is increased to the set value. At this time, the casting slurry is poured into the casting base belt, and the casting starts. The base tape is dried and shaped after being oriented by a rotating magnetic field, called green body by cutting, and called finished product after being sintered in a muffle furnace at 1100-1300 °C.

The beneficial effects brought by the technical solution of the present invention:

(1) The magnetic field provided by the electromagnet can be flexibly adjusted according to the material formed by changing the current, from 100 to 2000Gs;

(2) The use of the upper and lower electromagnets can make the distribution of the magnetic field in the middle region, especially in the thickness direction of the cast film, more uniform;

(3) The magnetic field generated by the rotation of the upper and lower electromagnets is equivalent to a magnetic field that changes in direction in the plane to the cast product, and when the rotation speed is different, the total magnetic field size is also in a continuous cycle. The periodic change of direction and size can play the role of micro-vibration of the material in the casting slurry, which is beneficial to reduce the resistance during particle orientation, thereby improving the degree of orientation. If only a unidirectional magnetic field is used, about 50% of the particles of the planar hexagonal ferrite have the X-Y plane not parallel to the substrate, but with the solution of the present invention the ratio is less than 5%.

Description of drawings

Fig. 1 is the structural representation of the present invention;

2 is a schematic diagram of the prior art planar hexagonal ferrite particles in a unidirectional magnetic field;

FIG. 3 is a schematic diagram of an available area in the prior art.

Detailed ways

The specific technical solutions of the present invention are described with reference to the embodiments.

As shown in Figure 1, the magnetic field of the tape casting orientation forming device that can be continuously produced includes electromagnets arranged above and below the tape casting base respectively;

The two electromagnets are respectively fixed by the bracket 3 , and the electromagnets can rotate on the bracket 3 with the bracket 3 as the axis.

The cross-section of the electromagnet is a chamfered rectangle.

When the electromagnet is perpendicular to the casting film, the two ends exceed the width of the casting film by more than 10 cm. If the rotation speeds of the two electromagnets are inconsistent during use, there will be an included angle between the two electromagnets. The magnitude of the current in the electromagnet is required to be adjustable, and is adjusted with a sliding rheostat. The bracket 3 of the electromagnet is made of a non-magnetic material such as aluminum, and the bracket 3 can support the weight and allow the electromagnet to rotate around the bracket.

The magnetic field generator used for the orientation can be rotated and the rotation speed can be adjusted, which can orient the material in multiple directions. At the same time, the size and direction of the magnetic field undergo periodic changes to form microscopic vibrations inside the material, thereby ensuring that most of the flake particles are The X-Y planes are parallel to the casting substrate.

The continuous production of the tape casting orientation molding method:

Combine Z-type or Y-type ferrite powder with binder (such as polyvinyl butyral), plasticizer (such as dibutyl phthalate), dispersant (such as Triton), solvent (such as toluene) , anhydrous ethanol, n-butanol, etc.), mixed and stirred to form a flowable casting slurry;

Start the casting machine, the casting base belt 4 starts to move, the upper and lower electromagnets start to rotate, and the current is increased to the set value. At this time, the casting slurry 5 is poured into the casting base belt 4, and the casting starts. The casting base tape 5 of the extension slurry 5 is dried and shaped after being oriented by a rotating magnetic field, called green body by cutting, and called a finished product after being sintered in a muffle furnace at 1100-1300°C.

Claims (3)

1. The magnetic field of the tape casting orientation molding device that can be continuously produced is characterized in that it comprises electromagnets arranged above and below the casting base tape respectively; the two electromagnets are respectively fixed by a bracket, and the electromagnets can be used on the bracket as a bracket. The shaft rotates. 2 . The magnetic field of the tape casting orientation forming device that can be continuously produced according to claim 1 , wherein the cross-section of the electromagnet is a chamfered rectangle. 3 . 3. The tape casting orientation molding method that can be continuously produced, is characterized in that, adopts the magnetic field of the tape tape orientation molding device that can be continuously produced according to claim 1 or 2, and the method comprises the following process: Start the casting machine, the casting base belt starts to move, the upper and lower electromagnets start to rotate, and the current is increased to the set value. At this time, the casting slurry is poured into the casting base belt, and the casting starts. The base tape is dried and shaped after being oriented by a rotating magnetic field, called green body by cutting, and called finished product after being sintered in a muffle furnace at 1100-1300 °C.

Images